20
23. CENTRAL HEATING LOW PRESSURE SWITCH
Located on the on the return pipe (above the pump) the low pressure switch provides
protection for the boiler in the event of pressure loss in the primary system.
Voltage to the switch (22V dc) is supplied from the PCB junction J4 (left hand red wire)
and returns to the PCB J4 (right hand red wire). Providing the pressure in the boiler is
greater than 0.7 bar the contacts in the switch will be closed and the supply voltage will
return to the PCB J4 (left hand red).
Failure to detect sufficient pressure in the system will result in the boiler locking out with
fault 2 being displayed.
The switch has 3 terminals, however connections with the red wire should be made to
terminals marked “COM” and “NO”.
IMPORTANT. If using an un-insulated screwdriver to lever the terminals from the switch,
voltage from the switch terminals may short to boiler pipe work and damage the PCB.
25. GREEN LED POWER ON & BURNER FUNCTIONING
The green LED has two display modes:
A constant green light indicates the boiler is ready to supply hot water or central heating on
demand.
A flashing green light indicates the burner is firing and operating in either hot water or
central heating mode.
Voltage is supplied to the LED from the PCB J5 22V dc between (black and brown) when
in standby mode.
Voltage changes to pulse mode 22V dc to 0 v dc between (black and brown) when the
main burner flame is detected.
N.B. mains voltage is still present at the PCB until the supply voltage to the boiler is
isolated.
26. RED LED LOCK- OUT INDICATOR
In the event of a boiler malfunction the red LED will flash in a sequence of self diagnostic
fault codes to indicate the relevant fault with the boiler/system or components.
Voltage is supplied from J5 on the PCB 22V dc between (black and red) in the event of
lockout.
To Next Page
Loading...
